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Que: What is the total number of sports clubs that John and Sandy have?

(1) John has 40 percent more sports clubs than Sandy.

(2) Sandy has between 5 and 11 sports clubs.
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Que: What is the total number of sports clubs that John and Sandy have?

(1) John has 40 percent more sports clubs than Sandy.

(2) Sandy has between 5 and 11 sports clubs.


Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the total number of sports clubs that John and Sandy have

Let us assign a variable: Suppose John has j sports clubs and Sandy has s sports clubs.

Follow the second and the third step: From the original condition, we have 2 variables (j and s). To match the number of variables with the number of equations, we need 2 equations. Since conditions (1) and (2) will provide 1 equation each, C would most likely be the answer.

Recall 3- Principles and Choose C as the most likely answer. Let’s look at both conditions combined together.

Condition (1) tells us that John has 40 percent more sports clubs than Sandy and Condition (2) tells us that Sandy has between 5 and 11 sports clubs.

=> Converting into equation: j = s + 40%s = 1.4s and 5< s < 11

=> Since s is an integer => s must be 6, 7, 8, or 9

However,

If s = 6 => j = 1.4s => 1.4 * 6 => 8.4 cannot be the number of sports clubs that John has (∵ It’s a decimal number)

If s = 7 => j = 1.4s => 1.4 * 7 => 9.8 cannot be the number of sports clubs that John has (∵ It’s a decimal number)

If s = 8 => j = 1.4s => 1.4 * 8 => 11.2 cannot be the number of sports clubs that John has (∵ It’s a decimal number)

If s = 9 => j = 1.4s => 1.4 * 9 => 12.6 cannot be the number of sports clubs that John has (∵ It’s a decimal number)

If s = 10 => j = 1.4s =>1.4 * 10 => 14 can be the number of sports clubs that John has (∵ It’s a integer)

=> ∴ John has 14 sports clubs and Sandy has 10 sports clubs

=> Total number of sports clubs possessed by Paul and Mike: 14 + 10 = 24

The answer is unique, so the conditions combined are sufficient, according to CMT 2 - there must be only one answer.

Both conditions together are sufficient.

Therefore, C is the correct answer.

Answer: C
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Que: Machine A and machine B produce toys at their constant rates, respectively. In how many hours does machine A produce the total number of toys?

(1) Machine B produces 1,000 toys in 8 hours.
(2) The total number of toys that machine A must produce is 2,000.
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Que: Machine A and machine B produce toys at their constant rates, respectively. In how many hours does machine A produce the total number of toys?

(1) Machine B produces 1,000 toys in 8 hours.
(2) The total number of toys that machine A must produce is 2,000.

Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the value of \(t_1\) =>(2 machines: \(r_1 * t_1 = w_1\) and \(r_2 * t_2 = w_2\))

Follow the second and the third step: From the original condition, we have 6 variables (\(r_1, t_1, w_1, r_2, t_2,and w_2\)) and 2 Equations (\(r_1 * t_1 = w_1\) and \(r_2 * t_2 = w_2\)). To match the number of variables with the number of equations, we need 4 more equations. Since conditions (1) and (2) will provide 1 equation each, E would most likely be the answer.

Recall 3- Principles and Choose E as the most likely answer. Let’s look at each condition separately.

Condition (1) tells us that Machine B produces 1,000 toys in 8 hours => \(r_2 * 8 = 1,000\) => \(r_2= 125\)

Condition (2) tells us that the total number of toys that machine A must produce is 2,000 => \(r_1 * t_1=w_1= 2,000\)

Thus, the Work rate of Machine A is unknown => Cannot determine the unique value of \(t_1\).

The answer is not unique, so the conditions combined are not sufficient, according to CMT 2 - there must be one answer.

Both conditions together are not sufficient.

Therefore, E is the correct answer.

Answer: E
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Que: If the ratio of the numbers of men to women to children in a certain room is 4 to 7 to 9, how many people are in the room?

(1) The total number of men and women in the room is 11.
(2) The number of children in the room is between 8 and 10.
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Que: If the ratio of the numbers of men to women to children in a certain room is 4 to 7 to 9, how many people are in the room?

(1) The total number of men and women in the room is 11.
(2) The number of children in the room is between 8 and 10.

Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

Let us assign the variable: men (m) ; women(w) ; children(c)

Given: m = 4k ; w = 7k ; c = 9k – where ‘k’ is a positive integer

We have to find the total number of people in the room => 5k + 3k + 7k = 20k – We have to find the value of ‘20k’

Follow the second and the third step: From the original condition, we have 4 variables (m, w, c, and k) and 3 equations (m = 4k; w = 7k; c = 9k). To match the number of variables with the number of equations, we need 1 more equation. Since conditions (1) and (2) will provide 1 equation each, D would most likely be the answer.

Recall 3- Principles and Choose D as the most likely answer. Let’s look at each condition separately.

Condition (1) tells us that the total number of men and women in the room is 11

=> 4k + 7k = 11

=> 11k = 11

=> k = 1

Therefore, 20k = 20 * 1 = 20

The answer is unique, so condition (1) alone is sufficient, according to CMT 2 - there must be only one answer

Condition (2) tells us that the number of children in the room is between 9 and 11

=> 8 < 9k < 10

=> 9k = 9

=> k = 1

Therefore, 20k = 20 * 1 = 20

The answer is unique, so condition (2) alone is sufficient, according to CMT 2 - there must be only one answer

** Tip 1: When condition (1) = condition (2) => 95% likely that answer is D

Each condition alone is sufficient.

Therefore, D is the correct answer.

Answer: D
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Que: If a certain machine produces toys at a constant rate, how many minutes will it take the machine to produce 1,800 toys?

(1) It takes the machine 80 minutes to produce 50 toys.
(2) It takes the machine 6.4 minutes to produce 4 toys.
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Que: If a certain machine produces toys at a constant rate, how many minutes will it take the machine to produce 1,800 toys?

(1) It takes the machine 80 minutes to produce 50 toys.
(2) It takes the machine 6.4 minutes to produce 4 toys.

Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

DS question dealing with the work rate of one machine => rt = w

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the value of t – (1 machine rt = 1,800)

Follow the second and the third step: From the original condition, we have 2 variables (r and t) and 1 equation (rt = 1,800). To match the number of variables with the number of equations, we need 1 more equation. Since conditions (1) and (2) will provide 1 equation each, D would most likely be the answer.

Recall 3- Principles and Choose D as the most likely answer. Let’s look at each condition separately.

Condition (1) tells us that it takes the machine 80 minutes to produce 50 toys.

=> rt = w

=> r * 80 minutes = 50

=> Multiply by 36 both sides

=> r * 80 minutes * 36 = 50 * 36

=> r * 2,880 minutes = 1,800

=> Machine makes 1,800 toys in 2,880 minutes

=> t = 2,880

The answer is unique, so condition (1) alone is sufficient, according to CMT 2 - there must be only one answer

Condition (2) tells us that it takes the machine 6.40 minutes to produce 4 toys.

=> rt = w

=> r * 6.40 minutes = 4

=> Multiply by 450 both sides

=> r * 6.40 minutes * 450 = 4 * 450

=> r * 2,880 minutes = 1,800

=> Machine makes 1,800 toys in 2,880 minutes

=> t = 2,880

The answer is unique, so condition (2) alone is sufficient, according to CMT 2 - there must be one answer.

** Tip 1: When condition (1) = condition (2) => 95% likely that answer is D

Each condition alone is sufficient.

Therefore, D is the correct answer.

Answer: D
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Que: When the equation \(x^2 + ax + b = 0\) has roots p and q, what is the value of p + q?

(1) a = 5.
(2) b = -6.
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Que: When the equation \(x^2 + ax + b = 0\) has roots p and q, what is the value of p + q?

(1) a = 5.
(2) b = -6.

Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the value of p + q.

=> Given: \(x^ 2 + ax + b = 0\) has ‘p’ and ‘q’ as its roots.

=> (x – p) (x – q)=0 => \(x^ 2 – (p + q)x + pq = 0\)

=> a = -(p + q) and b = pq

=> We have to find the value of a

Condition (1) tells us that a = 5.

=> a = 5 = -(p + q)

=> -( p + q) = 5

=> p + q = -5

The answer is unique, so condition (1) alone is sufficient; according to CMT 2 - there must be only one answer.

Condition (2) tells us that it b = -6.

=> b = pq = -6

=> If p = 2; q = -3, then pq = 2 * (-3) = -6 => 2 + (-3) = 2 - 3 = -1

=> But if p =3; q = -2, then pq = 3 * (-2) = -6 => p + q = 3 + (-2) = 1

The answer is not unique, so condition (1) alone is not sufficient; according to CMT 2 - there must be only one answer.


Condition (1) alone is sufficient.

Therefore, A is the correct answer.

Answer: A
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Que: \(\frac{(3^{a + b} )}{(3^{a - 2b})} = ? \)

(1) a = 4.
(2) 3b = 8.
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Que: \(\frac{(3^{a + b} )}{(3^{a - 2b})} = ? \)

(1) a = 4.
(2) 3b = 8.


Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Second of the seven properties of exponents: \(\frac{a^m }{ a^n} = a^{m - n}\)

Multiplication of the same base numbers with the same or different exponents = Addition of the exponents

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the value of \(\frac{(3^{a + b})}{(3^{a - 2b})}\)

Second property of exponents: \(\frac{(3^{a + b})}{(3^{a - 2b})} = 3^{a + b –( a – 2b)} = 3^{3b}\)

We have to find the value of 3b

Condition (2) tells us that 3b = 8

=> \(3^{3b} = 3^8 = 6,561\)

The answer is unique, so condition (2) alone is sufficient, according to CMT 2 - there must be one answer.

Condition (1) tells us that a = 4

=> Cannot determine the unique value of 3b

The answer is not unique, so condition (1) alone is not sufficient, according to CMT 2 - there must be one answer.

Condition (2) alone is sufficient.

Therefore, B is the correct answer.

Answer: B
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Que: How many distinct positive factors does the integer m have?

(1) \(m = p^2 q\), where p and q are distinct positive prime numbers.
(2) The only positive prime factor of m is 2.
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Que: How many distinct positive factors does the integer m have?

(1) \(m = p^2 q\), where p and q are distinct positive prime numbers.
(2) The only positive prime factor of m is 2.


Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the number of distinct positive factors of the integer m

Follow the second and the third step: From the original condition, we have 1 variable (m). To match the number of variables with the number of equations, we need 1 equation. Since conditions (1) and (2) will provide 1 equation each, D would most likely be the answer.

Recall 3- Principles and Choose D as the most likely answer. Let’s look at each condition separately.

Condition (1) tells us that \(m = p^2q\), where p and q are distinct positive prime numbers.

The number of positive factors of a number N, expressed in its prime form as \(N = p^xq^y\), where p and q are distinct primes, is given by (x + 1) (y + 1).

=> \(m = p^2q\). Thus, the number of positive factors = (2 + 1) (1 + 1) = 6

The answer is unique; condition (1) alone is sufficient according to Common Mistake Type 2 which states that the answer should be a unique value.

Condition (2) tells us that the only positive prime factor of m is 2.

Here, m can take multiple possible values. For example, 2, 2 2, 2 4, etc. all have 2 as the only prime factors. However, the number of factors of each of the above numbers is different.

The answer is not a unique value; condition (2) alone is not sufficient according to Common Mistake Type 2 which states that the answer should be a unique value.

Condition (1) alone is not sufficient.

Therefore, A is the correct answer.

Answer: A
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Que: If p and q are integers, what is the value of (q - p)?

(1) \(pq = 12 \)
(2) \((p + q)^2 = 84\)
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Que: If p and q are integers, what is the value of (q - p)?

(1) \(pq = 12 \)
(2) \((p + q)^2 = 84\)


Solution: To save time and improve accuracy on DS questions in GMAT, learn and apply the Variable Approach.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Visit https://www.mathrevolution.com/gmat/lesson for details.

Now we will solve this DS question using the Variable Approach.

Let’s apply the 3 steps suggested previously.

Follow the first step of the Variable Approach by modifying and rechecking the original condition and the question.

We have to find the value of p + q – ‘p’ and ‘q’ are integers

Follow the second and the third step: From the original condition, we have 2 variables (p and q). To match the number of variables with the number of equations, we need 2 equations. Since conditions (1) and (2) will provide 1 equation each, C would most likely be the answer.

Recall 3- Principles and Choose C as the most likely answer. Let’s look at both conditions combined together.

Condition (1) tells us that \(pq = 12\) and condition (2) tells us that \((p + q) ^2 = 84\)

=> \((p + q)^2 = 84\)

=> \(p + q = ± 8\)

=> If p = 2 and q = 6 then \(pq = 12 \) and \((p + q)^2 = 84\). Therefore, q - p = 4

=> But if p = -2 and q = -6 then \(pq = 12\) and \((p + q)^2 = 49\). Therefore, q - p = -4

The answer is not a unique value; both conditions combined are not sufficient according to Common Mistake Type 2 which states that the answer should be a unique value.

Both conditions together are not sufficient.

Therefore, E is the correct answer.

Answer: E
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Que: Set S is a set of 11 consecutive integers. Is an integer ‘6’ present in Set S?

(1) The integer −3 is present in the set.
(2) The integer 9 is present in the set.
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